This invention relates to a charged-particle beam apparatus, and more particularly to a charged-particle beam apparatus for observing a specimen introduced in a gap between upper and lower magnetic poles of an objective lens, wherein there is provided a specimen stage which permits observation of a large-diameter wafer which is inclined.
In an electron microscope, for example, if a large working distance from the center of the objective lens to the specimen is set, then the aberration of the objective lens becomes large, so that a high resolving power cannot be obtained unless a high accelerating voltage of the objective lens is used.
Therefore, as disclosed in JP-A-58-161235, in recent years, a method has been practiced in which a specimen is introduced between the upper and lower magnetic poles of the objective lens with the result that the specimen can be observed with less aberration of the objective lens.
With an electron microscope having such a construction, the interpole gap between the upper and lower poles is so narrow that a conventional large specimen stage cannot be used in its present size, and therefore, it is necessary to make some contrivance for the specimen stage.
In JP-A-61-64055, for example, there have been proposed a method in which the specimen stage is made in a cantilever type support structure and a specimen is observed while it is moved from outside, and another method in which the ends of the upper and lower poles are pointed and the specimen is inclined at an elevated angle.
In JP-A-62-291849, there has been proposed a method in which the specimen stage is constructed with the bottom wall of the lower magnetic pole as a base.
With the specimen stage having a cantilever type support structure as revealed in the above-mentioned JP-A-61-64055, it is difficult to move the specimen slightly in the X-Y or horizontal direction, and since the end portion of the specimen stage is supported in the form of a cantilever in the magnetic path of the objective lens, the specimen observing section is susceptible to effects of external vibration, and it is difficult to observe the specimen with a high resolving power.
As for a method of inclining the specimen, the only proposal has been to shape the upper and lower magnetic poles to allow inclining to an elevated angle, but no concrete specimen inclining method has been proposed.
On the other hand, in JP-A-62-291849 mentioned above, though it has been proposed to construct a specimen stage which moves in the X and Y directions, by basing it on the inside bottom face of the lower magnetic pole, no concrete form of construction for cutting off the effects of external vibration has been suggested. In addition, no construction for inclining the specimen has been disclosed.